ERAP2 and spondyloarthropathy: The similarities between BD and MHC-I-associated spondyloarthropathies, anterior uveitis, and birdshot uveitis have been described [22] and include antigen processing genes endoplasmic reticulum aminopeptidases (ERAP1 and ERAP2) and the interleukin-17 (IL-17) pathway gene interleukin-23 receptor (IL-23R), thus implicating MHC-I peptide presentation as a mechanism involved in these MHC-I-related spondyloarthropathies.